Neurones and Action Potentials Quiz

What is the main function of the myelin sheath in neurones?

• To produce neurotransmitters

• To act as an electrical insulator

• To generate action potentials

• To reduce the size of the axon

What are the gaps between Schwann cells called?

• Synaptic clefts

• Axon terminals

• Nodes of Ranvier

• Depolarisation zones

What happens during the stimulus phase of an action potential?

• Na⁺ ion channels close

• K⁺ ion channels open

• Na⁺ ions diffuse into the neurone

• Sodium-potassium pumps activate

What is the threshold potential required to trigger an action potential?

• -70mV

• -55mV

• 0mV

• +30mV

During depolarisation, which ion is responsible for making the inside of the neurone more positive?

• Potassium (K⁺)

• Sodium (Na⁺)

What occurs during the repolarisation phase of an action potential?

• Na⁺ ion channels open

• K⁺ ion channels open, and K⁺ ions exit the cell

• The membrane becomes more positive

• Myelin sheath repairs the axon

Why does hyperpolarisation occur after repolarisation?

• K⁺ channels close too slowly, allowing too many K⁺ ions to exit

• Na⁺ ions flood into the neurone

• The sodium-potassium pump fails temporarily

• Schwann cells stop functioning

What restores the resting potential after an action potential?

• Voltage-gated Na⁺ channels

• Sodium-potassium pump

• Diffusion of Cl⁻ ions

• Reopening of Na⁺ channels

During the refractory period, why can’t a new action potential occur?

• Na⁺ and K⁺ channels are inactivated

• The myelin sheath prevents ion flow

• The membrane potential is at +30mV

• The sodium-potassium pump is inactive

What is saltatory conduction?

• The movement of ions along the entire axon

• The generation of action potentials at every part of the axon

• The jumping of action potentials between nodes of Ranvier

• The transmission of signals through synapses